Pathology Commons^™

Phi-1, An Endogenous Inhibitor Protein For Protein Phosphatase-1 And A Pan-Cancer Marker, Regulates Raf-1 Proteostasis, Jason Kirkbride, Garbo Nilsson, Jee In Kim, Kosuke Takeya, Yoshinori Tanaka, Hiroshi Tokumitsu, Futoshi Suizu, Masumi Eto

Kimmel Cancer Center Faculty Papers

Raf-1, a multifunctional kinase, regulates various cellular processes, including cell proliferation, apoptosis, and migration, by phosphorylating MAPK/ERK kinase and interacting with specific kinases. Cellular Raf-1 activity is intricately regulated through pathways involving the binding of regulatory proteins, direct phosphorylation, and the ubiquitin-proteasome axis. In this study, we demonstrate that PHI-1, an endogenous inhibitor of protein phosphatase-1 (PP1), plays a pivotal role in modulating Raf-1 proteostasis within cells. Knocking down endogenous PHI-1 in HEK293 cells using siRNA resulted in increased cell proliferation and reduced apoptosis. This heightened cell proliferation was accompanied by a 15-fold increase in ERK1/2 phosphorylation. Importantly, the observed …